The Sydney rock oyster (Saccostrea commercialis) as estuary condition: some preliminary observations.

A series of studies have been directed towards monitoring the condition and status of New South Wales estuaries (eg. Bell and Edwards, 1980; West et al., 1984). Investigations by this author is suggest that the Sydney rock oyster, its production rates and health, may provide a useful indication of estuary condition. Firstly, it is evident that oysters must have the proper environment in order to multiply and to grow to marketable size. For this to occur, physical, chemical and biotic attributes of estuarine must conform to the range of oyster growth requirements and sanitation. These attributes of estuarine waters are affected by land use within coastal catchments. Land use impacts may be classified in one of the following groupings; • Enrichment of waters (loading of the estuarine system via input of phosphates and nitrates); • Pollution of waters (by poisons and inert suspenoids); • Restructuring morphometrically (by damming, channelization, infilling of wetlands and sedimentation); • Biological loading (introduction of non-native species); and • Harvesting of renewable resources (by either carefully regulated or opportunistic means). For simplicity in later discussion the resulting estuarine environment is referred to in this paper as the ‘estuary condition’. Analysis of commercial production rates of Saccostrea commercialis may provide an indication of the condition of a particular estuary.